Posted
by
Soulskill
on Saturday July 06, 2013 @08:37AM
from the gotta-entertain-their-cats dept.

New submitter Ahmed Shaban writes "Why do protesters in Cairo use laser pointers? At the beginning, they were used to light up snipers on rooftops. Later, it just became fashionable to use them, and such things spread very fast among the youth of Cairo, who can find the high power laser pointers for sale on the sidewalks. The article contains amazing photos of a chopper lit up by green laser pointers."

With the Egyptian military completely on board with the protesters this time around, I guess the laser pointers dont have much actual purpose anymore.

Its actually quite remarkable what is happening there. More people were protesting than had voted for the president because the president decided that their constitution didnt apply to him, so the military takes down the president in response but remarkably doesnt assume power.

How many countries actually have a military that would do this sort of thing? I'm fairly certain that mine, with a military that runs an agency well known now for violating the constitution, would not.

The military puts the current president under house arrest. Along with the Cabinet, and has warrants out for several hundred other high officials. Then, they (the military) appoint some other guy to be president. The only reason this new guy is there is because the military heads said "OK dude...you're up". He knows very well which side his peta bread is buttered on.

A coup is a coup, backed or not by the population. You should have trialed that guy instead of having the military take power and put a puppet. And if you can't bear waiting for the next election, change the constitution so that there is a mechanism to revoke the president and other elected officials.

Well i suppose a country with 40 years without democracy couldn't bear it more than a single one of it. I guess that dictator movie guy was right...

Well with Morsi in power and his el-presedente like powers the chance of something like "a mechanism to revoke the president and other elected officials" is nil. Though I have a much bigger suspicion that the military rebelled because Morsi and rest of the muslim brotherhood wanted them to jump into Syria, and Nigeria and support the islamo-facists there.

Oh really, and what would you have done if you were the military and the current president was trying to turn the country into a theocracy, replacing police, judges and school principles with his cronies?

Also, apparently the officials being arrested and the TV stations being closed are because they were encouraging their supporters to be violent.

I dunno. If someone staged a coup in the US, I'd be 'encouraging people to be violent' against it as well.

What if 50 million people in the US took to the streets in protest of the government?

That is essentially what just happened in Egypt. 17% of the people took to the streets! The largest protest in the history of the world at 14 million people.

Its gotta be extremely bad to get 17% of the people actively protesting, so when you say 'staged a coup' I honestly wonder exactly how ignorant you are of what just happened in Egypt. Only read and watch American news?

I'm not ignorant to what's happening, but what part of my sentence was factually inaccurate? Did the military not take over the country and appoint a new leader? Is that not the textbook definition of a coup d'etat?

I'm well aware of the various failings of the Morsi administration, but let's be clear: if 17% of the population of the US was protesting the Obama administration, and the Joint Chiefs had suspended the rule of law embodied by the Constitution to appoint John Roberts as President, it would not be

Just because a government is democratically elected doesn't mean it's a democracy. History is full of democratically elected governments that then turn into totalitarian regimes.

If Obama woke up tomorrow and ordered that all Tea Party members be arrested, I would expect our military to essentially remove him from office - in the immediate case by ignoring him, and in the longer case by Congress impeaching him and removing him from office - which would still require the cooperation of the military (they'd have to decide to listen to Congress and not the President.)

In Egypt, there isn't really a constitutional mechanism to get rid of a leader who, while democratically elected, isn't fulfilling his responsibilities as a democratic leader, so the best thing they have is the Army takes care of it.

So while this may technically be a coup in that the elected leader is being removed from office through a non-elective means, it's not necessarily undemocratic, if you believe the elected leader is abusing the freedoms of the people and the coup is to create the opportunity for someone who does respect the rights of the people to be elected.

If Obama woke up tomorrow and ordered that all Tea Party members be arrested, I would expect our military to essentially remove him from office - in the immediate case by ignoring him, and in the longer case by Congress impeaching him and removing him from office - which would still require the cooperation of the military (they'd have to decide to listen to Congress and not the President.)

This is what Abraham Lincoln did and he is considered a hero.

Even heroes do really shitty things from time to time.

Did Abraham Lincoln violate the Constitution, and should he have been called to account for it?

Yes, and maybe. Sometimes the spirit of the law is fulfilled in different ways than by following the letter of the law, but in the case of Lincoln, it isn't clear that it was necessary.

Oh, and FDR, who probably saved the world from the Nazis by supplying the Soviets and Britain against popular opinion in the US (before Pearl Harbor), his government opened concentration camps for Japanese Americans. Being a hero doesn't mean everything you do is heroic.

Psst: The US supports this takeover. There's a long history and tradition of supporting dictators against the people, as long as the dictators are nominally friendly towards US policies. If anything, the newspapers here in the US paint a picture of the people rising to overthrow a despot, which isn't what's happening at all.I fear you might have been hit by American and right-wing propaganda here, and don't even realize it.

Part of the problem over the last year has been that democracies need checks to en

14 million is utter bullshit. The figure's original source? an unnamed " military source".

The biggest protest was 500,000, the next biggest was Alexandria at 'a few 100,000'. After that you've probably a bit of long tail but the numbers likely plummeted drastically. A figure of 1-1.5mill seems most likely.

Think about it, you've people too old, too young, not physically able, too scared, to busy with work, people living in a low density populated area, people who don't care enough, people who just flat

The transitions in Egypt have been politically guided by the military, most likely in co-operation with some foreign help - for instance the US, because the US has a lot of interest in Egypt (supporting the past dictatorship too). The group who managed the first revolution and this one perfectly know how to channel the energy of the masses.

Military should ideally be a politically neutral force. That's not true anywhere.

Yeah, the US traditionally champions democracy with the caveat that the people elected had better be who the US wants to see in power, or your democratic process will be summarily and violently overthrown. Egypt is just one more chapter in this book of aggression.

How many countries actually have a military that would do this sort of thing? I'm fairly certain that mine, with a military that runs an agency well known now for violating the constitution, would not.

What you fail to realize is that the US military is ALREADY running the show.The appearance that civilians are running the show is kept up to placate themasses. You should join in with them in a chorus of "baaaa !!!"

There are 4 main factions in Egypt, and certainly not all of them are happy with the military... clearly the muslim brotherhood is no longer happy with them. I imagine the minor groups like the Christians are extremely happy now.

I work with a man from Egypt, a Christian with family over there. I asked him what he thought about all this and his eyes lit up, "my family is finally free."

I hope he's right about that. I suspect he may have thought that the last time.

Overthrowing dictators is always a good thing, but I consider it a tossup at best as to whether the new leadership actually wants to rule democratically. Egyptians voluntarily elected an Islamist party last time, and even if the Muslim Brotherhood is out, Islamist sentiments remain. I will hope for better, but I'll believe it when I see it.

Yes, the Egyptian military is unusual is that they are not an obvious kleptocracy like most other military juntas. I'm sure that there are senior military members, however, who are economically and politically benefiting from the status quo, but mostly they seem to want to hold on to their position as a mostly secular, stabilizing influence. It's not like they did such a great job before Mosari, however to be fair, it's not clear that anyone could do a whole lot better.

Turkey comes to mind. The military there has on several occasions defended the constitutions againts attack from government, and then handed the keys back over to the ones who, by the constitution, should hold them; namely the people (trough elections)

Laser pointers can cause permanent damage, but it's really damned hard to do at any distance against a moving target. It's akin to banning slingshots with rubber pellets because they could cause permanent blindness against a close range stationary target.

...are the moronic A/Cs on/. who seem happy to denigrate the Egyptian people for celebrating the peaceful overthrow of a useless leader.
The fact that the army has removed these incompetants and are immediately handing power back to the people is un-precedented and incredible. The Egyptian people and army could teach some other nations a thing or two, I think, not to mention some of the ignorant bigots who plague/.

I don't think Slashdotters are denigrating the Egyptians for their celebration as much as they are pointing out what a bad idea illuminating aircraft with laser pointers is. In the USA and other countries, doing this sort of thing with laser pointers is a sign of aggression against low flying aircraft and is illegal. So TFA points out the positive motivation behind what we have seen in the media. Even if we think its still a bad idea.

By all objective measures Morsi's government were useless. The country was falling apart and none of the promises they made pre-election were being acted on.
I don't claim to be intelligent, but like to think that my views are based on knowledge and understanding, not some idiotic racial/religious stereotyping.

You'll need to be more detailed, because "not keeping promises" is pretty much the definition of a politician and half the people of any given country will say it's "falling apart" under the current government.

You'll need to be more detailed, because "not keeping promises" is pretty much the definition of a politician and half the people of any given country will say it's "falling apart" under the current government.

Ha, I can't argue with that!
As for details and citations, c'mon, this is slashdot!

Glad to hear that you think that 30 people out of 14 million dead over the course of 2 days isnt an extraordinarily low death rate. Its like they stopped aging, stopped having heart problems, stopped having car accidents, and their cancers went into remission.

Here is an idea, instead of morning the 30 people that died, rejoin that hundreds that should of died amazingly did not.

Is the fact that fewer people died than actually should have through normal day to day life confusing you? "oh my god.. 30 people died!" -- guess what, 30 people died since I started typing this.

Is the vote of someone who doesn't take to the streets worth less than the vote of someone who does?

The former's *vote* may not be worth any less, but s/he will certainly have less of an actual voice in said democracy. Likewise will the person who does not participate in any other form of political activism (e.g., attending/following local government functions, actively volunteering for political candidates, supporting groups that protect one's interests) have less of a voice in a democratic government than those who do.

Ha, if I relied on American news I wouldn't know a bloody thing! Thankfully I'm a European (of sorts). I never said the current situation was peaceful, or desirable. The coup was peaceful, but subsequently the opposing sides have started skirmishing, which is to be expected, and it does look like the army might be a bit more active than before in intervening. This is clearly not good.
I also do have serious reservations about the principle of the army removing democratic governments. While I can't condone this, in this particular case it probably averted a civil war, so was the lesser of two evils.
This is not a good situation at all, but that is not what my original post was about. I posted because half the preceding posts were full of ignorance and bigotry and it pissed me off, that's all.

Agreed. We use 10mW and 20mW green lasers for star pointing in astronomy. They're clearly visible to nearby users but get more than about 10-20ft away and that's no longer the case. Judging by the pictures in TFA the ones the protestors were using were probably in the 150mW+ range.

Well, if you actually want to blind someone, you aim it properly and use it in a pulsed mode. Much lesser chance of hitting something you didn't intend to. But of course, the "enraged crowd" part is kind of at odds with playing nice.

You can see the ones in the Egypt videos because they're just really powerful. Far more powerful that what is legally available in the USA without a variance.

You didn't read the article at all did you?

As crowds packed Tahrir Square in the centre of Cairo to celebrate the overthrow of President Mohammed Morsi on Wednesday night, three things filled the air - noise, fireworks and, unusually, laser beams.

but I don't believe for a moment that it'll ignite anything at a distance of several hundred feet

Although atmosphere does reduce the power, it's columnated light and in a vacuum anyway it would not lose any of its power. Dust, fog, humidity in the air will lower the power, but also cause you to be able to see the beam in the air. If you can't see the beam of a laser, it's likely delivering very close to 100% of its output power on target.

Years ago, when laser pointers were expensive, I had a 5mw red laser that we tested at 1/4 mile. It lit up an entire dumpster very nicely. (lenses weren't that good back then, it wouldn't hold a point for more than 25 feet or so, and TONS of scatter)

But on the other issue of power, just because it's a laser doesn't make it any more destructive than something else of the same power. A 100w lightbulb puts out 100x the power of a 1w laser pointer. And you don't see lightbulbs catching helicopters on fire. (even if focused in a spotlight) The only reason 1w lasers catch paper on fire is they're concentrating 1w of power into a 2mm x 2mm area. That would probably feel like a match at 1/2", enough to light paper. That's not going to melt metal obviously, at any range. The laser just lets you project that "half inch from a match" out several hundred yards. It doesn't make it more (or less) intense.

Somewhat back on topic though... wow.... that flight had to SUCK for those helicopter pilots. Someone hits one 727 with a laser pointer and the whole city loses their mind and the swat team rolls. That heli looks like it had 3-4 dozen green and at least two blue pointed at it. They would have to be out of their minds to look down except through cameras, and imagine the refractions going on inside the cockpit, with greens and blues scattering off all the shiny things. I bet that is an incredibly effective deterrent for the pilots.

Ironic, they sent in the helicopters as a show of force, and got driven off by the demonstrators using cheap, commonly available tech. Sort of like making the water canon truck leave by throwing rocks at it. Embarrassing.

Interestingly enough, the crowd on Tahrir square was actually cheering the military on. Every time the helicopters showed up it was cause for celebration. The crowd likely had no idea that they were annoying the pilots.

Most laserpointers are 1mW or less, so they don't reflect enough particulates in the air unless it's foggy. The green ones in the video are usually at least 5mW, which is powerful enough to reflect off enough dust in the air to be visible under normal conditions.

It's one of the big errors that scifi movies have with lasers in space combat (the other error being that laser pulses move slow enough to be seen). even with insanely powerful lasers, they'd be practically invisible in space because there's nothing for them to reflect off. Unless, of course, you want to pretend that all laser space battles take place in dust or gas clouds...

It's one of the big errors that scifi movies have with lasers in space combat (the other error being that laser pulses move slow enough to be seen). even with insanely powerful lasers, they'd be practically invisible in space because there's nothing for them to reflect off. Unless, of course, you want to pretend that all laser space battles take place in dust or gas clouds...

Thus the use of sandcasters in the
Traveller RPG [wikipedia.org]. Basically dump bags of sand into space around your ship to absorb/reflect any laser weapons.

It's one of the big errors that scifi movies have with lasers in space combat (the other error being that laser pulses move slow enough to be seen). even with insanely powerful lasers, they'd be practically invisible in space because there's nothing for them to reflect off. Unless, of course, you want to pretend that all laser space battles take place in dust or gas clouds...

Thus the use of sandcasters in the
Traveller RPG [wikipedia.org]. Basically dump bags of sand into space around your ship to absorb/reflect any laser weapons.

And lots of other SciFi, such as the Earth Strike series by Ian Douglas (a pseudonym of ex-Navy W.H. Keith). Too bad for Hollywood, which requires an unthinking and/or ignorant audience, or somehow equates SciFi with unscientific Fantasy.

It's one of the big errors that scifi movies have with lasers in space combat (the other error being that laser pulses move slow enough to be seen

But combine those two errors, and we have a bit less of an error - Simply one of nomenclature rather than physics.

Pulses of light like we see in the movies would would more likely come from some sort of particle beam. It would travel slower than the speed of light, and most likely radiate energy during its trip (thus making it visible from the side).

I thought some sci-fi got around that by saying those beams weren't lasers at all, but instead were plasma or perhaps something altogether different. According to Star Trek canon, for instance, their beams are "phasers" which are actually FTL; in a battle between FTL-capable ships, lasers would be pretty useless after all since the ships could easily outrun the lasers.

Space is full of dust on an astronomic scale. On a scale relative to humans, it's a void. When projecting a narrow beam of light through space, the odds of it hitting enough dust to give a visible reflection to an observer is pretty small. The average density of space* is around one atom per cubic centimer. That means you would have to project a laser with a 1cm diameter about three million kilometers before it interacted with enough atoms to constitute a single single spec of dust. That's nearly eight time

Enough energy to vapourize a ship would have enough energy to create particle/anti-particle pairs all along its length. The creation/annihilation of these particles would give off radiation in all directions.

I am sorry but you are plain wrong! "Enough energy to vapourize a ship" can be achieved with an infrared laser (photons of energy below 1 eV). Even if you allow for multiphoton interactions it is orders of magnitude below the threshold for the pair creation (1.02 MeV for electron-positron) . There aro no lasers that produce photons in MeV range. Also, the annihilation of electron and positron, which is the lowest energy particle-antiparticle anihilation, produces gama photons ~.51 MeV which are quite invisible to humans.

Technically they did have democracy and got what they voted for, but what they didn't have were safeguards to ensure that a president couldn't just declare himself dictator for life after being elected. And so that's what he tried to do as early as possible. They need to adjust their system, institute checks and balances, constitutional changes requiring national referendums etc.

My understanding is that they didn't really have much of a choice in who to vote for. It was between a known bad guy and a probably bad guy, so they went with the latter due to lack of choices to begin with. Is it really a free and democratic election if you don't have choices?

If it were so easy, many South American countries would have become as prosperous and democratic as the US since their constitutions were basically copies of the US Constitution. Yet, somehow, it didn't really work.

You can see the same in many former British colonies. If you read their Constitution, you'll see that they're not much different from what you find in any modern democracy. Bill of rights, checks and balances, constitutional protections for both negative and positive rights. They also inherited the common law tradition and much of their legislation is copy-pasted from UK legislation circa 1960. It's so similar in theory that UK-trained lawyers can usually practice with minimum to nil extra training, as most of the legal education is done from UK textbooks and case books anyway.

Yet, in practice, it's quite different. Sure, you have the same theoretical protections, but they do little good when everyone is free to ignore them. It's nice to tell the courts that they have to be independent and fair, but how do you guarantee that?

"They need to adjust their system, institute checks and balances", etc. is all wishful thinking. It's about as useful as telling a developing country that all they need to do is grow. It's true but pretty useless as far as advice goes. The tricky part is knowing how to move from the equilibrium where the law is widely ignored, where formal checks and balances don't work, where the constitution is not worth the paper it's written on, to a better equilibrium. As far as I can tell, no-one has yet found a magic recipe for that because things are usually the way they are for a reason. It's not like bad institutions just spring up at random: they are usually people who have an interest in maintaining the status quo, and we were able to see times and times again that removing whoever happens to be in power doesn't do much to solve the structural problems and can even lead to worse outcomes (Iraq? Libya?).

You'd likely find an "Emergency Powers" clause which allow the President (or whatever he's called) to rule by decree. It only takes one clause like that to make a complete mockery of the rest of the constitution.

Morsi tried to "declare himself dictator for life after being elected."

Sorry, but citation needed. I've been Googling for this and can't find him guilty of anything above rank incompetence.

If anybody can show me what he did that was so bad other than being a crap leader or vague accusations of being devious and manipulative (of course he is! He's a frikkin' politician!) I'd love to see it.

The most factual account I can find is here [counterpunch.org] where author Esam Al-Amin says:

I was in the dorms at college when Obama was elected for the first time. His supporters rioted and caused a bunch of property damage and ruffed up people.There's also been cases of sports fans rioting when their team has won.

People do crazy shit to celebrate that just seems counterproductive to an outside observer.

I think they become stupid. It's a group dynamic thing. Take a reasonable person, put him in a group with those he subconsciously recognises as his 'tribe,' give them a cause to celebrate. Everyone bases their standards of behavior on everyone else in the group, so the apparent stupidity escalates rapidly.

If lasers are being sold for cheap on the street, odds are good that they're producing a wide range of wavelengths. The cheaper the laser, wider the range of wavelengths it emits. It's one of the reasons better lasers come with an IR filter to help reduce accidental blinding of observers.

If lasers are being sold for cheap on the street, odds are good that they're producing a wide range of wavelengths. The cheaper the laser, wider the range of wavelengths it emits. It's one of the reasons better lasers come with an IR filter to help reduce accidental blinding of observers.

Um, no. Not enough to say so, at least.What makes a laser a laser is that it is a single wavelength. The light amplification process itself only works on a specific wavelength, and weeds out other light. You have to put extra circuitry into a laser to get it to produce a wider range.

Some laser pointers do put out IR wavelengths as a byproduct of the way they're built. Low-power laser pointers aren't a problem, the IR simply isn't powerful enough to do anything. But with 100mW+ laser being sold to ordinary people, there is a very real IR hazard from cheaply-made badly-filtered (or not filtered at all) laser pointers, especially green laser pointers.

The reason it's so dangerous is that unless you have special dual-wavelength safety glasses, they'll only filter out the visible light, leaving the IR output to wreck havok on your eyes.

That assumes anyone is wearing safety glasses in the first place - which is pretty unlikely in this situation. Since the IR is in the same beam-path as the visible light, it isn't inherently any more dangerous for the typical person.

That sounds implausible to me. In fact I used to work with low-power (could put your hand in the beam without feeling it) IR lasers in college and we needed extra safety gear specifically because a stray beam could be shining into your eye without you noticing until serious permanent damage began to set in.

It may not cause dazzle or other forms of temporary blindness due to over-stimulated rods and cones, but except in extreme cases I believe such damage usually repairs relatively quickly, but its no less

What makes it a laser is how the light is produced. In most cases the lasers available to consumers are just very bight lamps with narrow bandwidth, good collimation, and not monochromatic.

It takes extra care to build a laser that produces only one frequency and even more care for the output to be coherent for any distance which is why holography and interferometry have problems with solid state lasers and gas laser are still used.

Police and cats have much in common1) They both enjoy stalking weaker prey2) They both enjoy toying with their prey3) They both have a love/hate relationship with lasers4) There's tons of videos on YouTube of them both doing dumb things

Most lasers over 5mW are already illegal to import to the US unless you have a specific commercial or industrial purpose. The lasers in the pictures are almost certainly at least 5mW or higher to be that visible in the air.

The "damage" the laser pointer could do to a plane is indirect. It can't destroy or harm the plane itself, but it can harm the pilot. It can of course cause eye damage if it happens to hit the pilot right in the eye, but any "near miss" that hits the cockpit can have adverse effects on the safety of the plane or chopper. It can startle the pilot, the sudden brightness of a laser hitting a target that scatters the beam (and with plenty of shiny surfaces in the cockpit, there's a lot of chances for that) can

If an aircraft is on auto-pilot, there's negligible risk.If an aircraft is currently under human control while cruising, there's a slight risk.If an aircraft is under human control while taking off, landing or performing any sort of maneuver, there's a reasonably significant risk.

Have you ever had someone shine a bright flashlight in your face? It's a lot like that. It causes you to jerk away, confuses you, and partially blinds you for anywhere from a few seconds to several minutes. Any of those can be deadly given that the person with the laser probably doesn't know if the aircraft is on autopilot or is preparing to land.

It's one of those laws where, sure, 98% of the time nothing bad will happen if you do it. But that last little bit of a time, something *really* bad could happen. So it's a felony.

While rare, ejection seats for helicopters aren't entirely unheard of. I'm too lazy to look it up but IIRC there are some Russian helicopters that have them. I believe the most common design is rocket powered and launches the pilot out sideways and away from the aircraft.